/*
 * @Author: szx
 * @Date: 2022-03-03 14:01:44
 * @LastEditTime: 2022-03-03 14:02:54
 * @Description:
 * @FilePath: \leetcode\100-199\104\104_2.js
 */
function TreeNode(val, left, right) {
    this.val = val === undefined ? 0 : val;
    this.left = left === undefined ? null : left;
    this.right = right === undefined ? null : right;
}

/**
 * @param {TreeNode} root
 * @return {number}
 */
var maxDepth = function (root) {
    if (!root) return 0;
    return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1;
};
